When sitting with a/c running, battery indicator goes to purple before the engine kicks in.
When sitting with heat running, battery indicator never goes to purple. The engine kicks and the battery indicator always remains in the green.
my question is, is this normal?
Seems kind of odd.
Thanks.

 

Not odd at all. Completely normal.

A/C needs the electrically driven compressor to provide cooling. The compressor is 200V 3 phase AC powered by the high voltage system through the inverter. When the engine is running, the HV battery runs the A/C. The engine comes on when the battery charge hits about 40% SoC and generally only runs long enough to bring the SoC up about 5-10%. A brand new battery can power the A/C full-blast for about 4 minutes in typical situations before the engine starts. Once the engine is running, it charges the battery AND powers the A/C.

Heat needs the engine running as the engine is the only source of cabin heat. It places almost no load on the HV system as the blower runs off the 12V system and only consumes about 5% of the electrical energy as the A/C. The engine comes on when additional heat is needed.